Returns garbage collector generation for the given object.

class B
  include ObjectSpace

  def foo
    trace_object_allocations do
      obj = Object.new
      p "Generation is #{allocation_generation(obj)}"
    end
  end
end

B.new.foo #=> "Generation is 3"

See ::trace_object_allocations for more information and examples.

Specifies a Proc object proc to determine completion behavior. It should take input string and return an array of completion candidates.

The default completion is used if proc is nil.

The String that is passed to the Proc depends on the Readline.completer_word_break_characters property. By default the word under the cursor is passed to the Proc. For example, if the input is “foo bar” then only “bar” would be passed to the completion Proc.

Upon successful completion the Readline.completion_append_character will be appended to the input so the user can start working on their next argument.

Examples

Completion for a Static List

require 'readline'

LIST = [
  'search', 'download', 'open',
  'help', 'history', 'quit',
  'url', 'next', 'clear',
  'prev', 'past'
].sort

comp = proc { |s| LIST.grep(/^#{Regexp.escape(s)}/) }

Readline.completion_append_character = " "
Readline.completion_proc = comp

while line = Readline.readline('> ', true)
  p line
end

Completion For Directory Contents

require 'readline'

Readline.completion_append_character = " "
Readline.completion_proc = Proc.new do |str|
  Dir[str+'*'].grep(/^#{Regexp.escape(str)}/)
end

while line = Readline.readline('> ', true)
  p line
end

Autocomplete strategies

When working with auto-complete there are some strategies that work well. To get some ideas you can take a look at the completion.rb file for irb.

The common strategy is to take a list of possible completions and filter it down to those completions that start with the user input. In the above examples Enumerator.grep is used. The input is escaped to prevent Regexp special characters from interfering with the matching.

It may also be helpful to use the Abbrev library to generate completions.

Raises ArgumentError if proc does not respond to the call method.

Returns the completion Proc object.

Returns the number of malloc() allocations.

Only available if ruby was built with CALC_EXACT_MALLOC_SIZE.

Returns the Base64-encoded version of bin. This method complies with RFC 4648. No line feeds are added.

Returns the Base64-decoded version of str. This method complies with RFC 4648. ArgumentError is raised if str is incorrectly padded or contains non-alphabet characters. Note that CR or LF are also rejected.

Set the default ACL to acl.

See DRb::DRbServer.default_acl.

Set the default ACL to acl.

See DRb::DRbServer.default_acl.

Returns an Array of option names of the method mid.

p FileUtils.options_of(:rm)  #=> ["noop", "verbose", "force"]

Takes a hash as its argument. The key is a symbol or an array of symbols. These symbols correspond to method names, instance variable names, or constant names (see def_delegator). The value is the accessor to which the methods will be delegated.

Tests for the presence of a --with-config or --without-config option. Returns true if the with option is given, false if the without option is given, and the default value otherwise.

This can be useful for adding custom definitions, such as debug information.

Example:

if with_config("debug")
   $defs.push("-DOSSL_DEBUG") unless $defs.include? "-DOSSL_DEBUG"
end

Tests for the presence of an --enable-config or --disable-config option. Returns true if the enable option is given, false if the disable option is given, and the default value otherwise.

This can be useful for adding custom definitions, such as debug information.

Example:

if enable_config("debug")
   $defs.push("-DOSSL_DEBUG") unless $defs.include? "-DOSSL_DEBUG"
end

Sets a target name that the user can then use to configure various “with” options with on the command line by using that name. For example, if the target is set to “foo”, then the user could use the --with-foo-dir=prefix, --with-foo-include=dir and --with-foo-lib=dir command line options to tell where to search for header/library files.

You may pass along additional parameters to specify default values. If one is given it is taken as default prefix, and if two are given they are taken as “include” and “lib” defaults in that order.

In any case, the return value will be an array of determined “include” and “lib” directories, either of which can be nil if no corresponding command line option is given when no default value is specified.

Note that dir_config only adds to the list of places to search for libraries and include files. It does not link the libraries into your application.

Returns compile/link information about an installed library in a tuple of [cflags, ldflags, libs], by using the command found first in the following commands:

1. If --with-{pkg}-config={command} is given via command line option: {command} {option}

2. {pkg}-config {option}

3. pkg-config {option} {pkg}

Where {option} is, for instance, --cflags.

The values obtained are appended to +$INCFLAGS+, +$CFLAGS+, +$LDFLAGS+ and +$libs+.

If an option argument is given, the config command is invoked with the option and a stripped output string is returned without modifying any of the global values mentioned above.

The path to standard location of the user’s configuration directory.

The path to standard location of the user’s .gemrc file.

Returns the status of the last executed child process in the current thread.

Process.wait Process.spawn("ruby", "-e", "exit 13")
Process.last_status   #=> #<Process::Status: pid 4825 exit 13>

If no child process has ever been executed in the current thread, this returns nil.

Process.last_status   #=> nil

Returns a new lazy enumerator with the concatenated results of running block once for every element in the lazy enumerator.

["foo", "bar"].lazy.flat_map {|i| i.each_char.lazy}.force
#=> ["f", "o", "o", "b", "a", "r"]

A value x returned by block is decomposed if either of the following conditions is true:

• x responds to both each and force, which means that x is a lazy enumerator.

• x is an array or responds to to_ary.

Otherwise, x is contained as-is in the return value.

[{a:1}, {b:2}].lazy.flat_map {|i| i}.force
#=> [{:a=>1}, {:b=>2}]

True if the gems in the system satisfy dependency.

Returns the destination encoding name as a string.

Returns the destination encoding name as a string.

Perform hostname verification following RFC 6125.

This method MUST be called after calling connect to ensure that the hostname of a remote peer has been verified.